How do I figure this out??

[phils88gmc]

Ok, I have this 88 GMC I got on a trade. It is lowered front and rear, I would like to put some nice wheels and tires on it and can't figure out the backspacing on the wheels, do to it being lowered. I have no clue in the world how much it is lowered. Does anyone know how to figure something like this out. I would like to go 20" in rear and 19" in front.

Now some one flipped the axle on top of the leaf springs and c-notched the frame. I can't tell if they put lowering leaf springs in the rear or not. There are no blocks in the rear either

The front has tubular lower control arms and i cant tell if the spindle and springs are aftermarket or not.

I just want to be able to order some wheels and tires and have the correct backspacing ready.

Here is a pic of it now....

[7T2]

Take a look underneath and see how much clearance you have with the wheels on it now. If, for example, you have 2 inches between the existing wheel and tire and the nearest suspension component or body part, figure you could add an inch to that and still be safe. Then take off the current wheels and tires and measure the backspacing on them. Then add the extra inch of clearance you have to the current backspacing measurement on the wheels to find out what you need on the new ones.